my pakcage in N9 contains a sqlite database file located in opt/myproject/Databases/

and i 've successfully connect the database through my codes
Then i do the following codes:

db.transaction(function(tx) {

tx.executeSql('CREATE TABLE IF NOT EXISTS Greeting(salutation TEXT, salutee TEXT)');
// Add (another) greeting row
tx.executeSql('INSERT INTO Greeting VALUES(?, ?)', [ 'hello', 'world' ]);

when i debug it with QT simulator ,it began error like the below description.

Error: attempt to write a readonly database Unable to fetch row

//And i 've found that ,if i deploy any files in the N9's opt/ directory ,i can only read and cant write to it .
What was wrong ,and how i could do to write the file???